1. Field of the Invention
The present invention relates to angular position sensors typically used as an input device for electronics having a graphical user interface.
2. Background Art
Angular input sensors, known as scroll wheels, scroll rings, jog wheels and the like, are intuitive input devices often used with a graphical user interface (GUI) for choosing between items that can be arrayed in some sense one-dimensionally, such as a list, or arrayed circularly, such as a list that wraps around. Selectable options or choices may be discrete, such as channels on a TV, or continuous, such as audio volume. Scroll wheels often consist of a flat disk or wheel. In use, a user touches the face or edge of the disk and rotates the disk in order to manipulate choices in the GUI.
Angular input sensors can be constructed as a touch sensitive annular surface. One example is the Apple iPod, a portable music player. A ring-shaped capacitive sensor on the face of the iPod reports the angular position of a finger touch, which in turn is used to manipulate menus on an LCD display.
To be useful in hand-held portable electronics, such angular sensors must meet severe space and power consumption requirements. Ideally, the sensor is measurable by a small microcontroller. To conserve scarce battery power the sensor should be compatible with waking the microcontroller from a low power sleep mode by a user's touch, as opposed to requiring the microcontroller to frequently wake and actively check for a touch. Angular sensors should be inexpensive, easy to manufacture and easily manufactured into an end product. Preferably, the design should be adaptable into a variety of shapes besides a simple circular ring.